Historical Content Note: The following material is reprinted from publications from throughout Fermilab's history. It should be read in its original historical context.

Meson Lab Opens for Business with a Big Order

drawing of meson lab

(Editor's Note: The NAL Meson Laboratory staff drove hard toward completion in 1972. Their efforts to finish were equalled only by the smashing success of the first experiments already carried out there. Art Greene, Physicist on the staff of the Director's Office, and Alan Wehman, Physicist of the Meson Laboratory, contributed the following information on this operational area of NAL.)

On Wednesday morning, September 20, 1972, the NAL Meson Laboratory completed a task difficult to surpass in the future - the completion of nine experiments within a four-day period. Over forty "stacks" of nuclear emulsions were exposed to 200 BeV protons. Physicists from Poland, India, France, Japan, the U.S.S.R., and the United States arrived at NAL for the International Conference with individual emulsion detectors, effectively bringing their experiments in their suitcases. It remained for the visiting physicists and NAL personnel to make the final preparations for the exposures.

Historically, nuclear emulsions were the detection media used for some of the first studies of high energy particle interactions. Due to their light weight and small size, they were frequently used as a detector of cosmic ray interactions in flights of high altitude balloons or satellites. The emulsion material itself is very similar to that used for photographic film, but is produced in sheets up to 1/16" thick and without a backing. A "stack" is formed by several layers of emulsion, bound together and sealed from light. Normally, the stack is exposed to a few hundred thousand particles, some of which interact in the emulsion material producing the interactions of interest to physicists. The emulsion layers are then mounted on glass plates, and undergo an elaborate development process to unveil the traces of particles. Analysis is done exclusively with microscopes, and it takes many months to locate and analyze a few hundred events of interest. Because of this, the primary effort for the experimenter follows the exposure and does not precede it, as with many high energy physics experiments.

This drawing shows the external proton beam path to the Meson Lab Target and the six secondary particle beams (M 1-6), produced from interactions in the target box (MTB). Also, the Main Laboratory Building (MLB) (under construction). Other buildings and enclosures on the line house the beams and the experiments which use the beams. Indicated also are the first experiments utilizing each beam (E-72, E4-I, E-69A, E-96, E-75, E-104)

The Japanese physicists, who participated in the effort under the direction of Dr. Niu of the University of Tokyo, recognized the need for a giant helium bag to reduce interactions of beam protons with air in a 200-foot section of beam line. They immediately set out to construct such an item, utilizing their many years of experience in constructing high altitude helium-filled balloons.

However, it was a clever technique devised by members of the NAL Switchyard Section that provided the essential ingredient. They were successful in shaving off just a few thousand protons from the billions of protons in the circulating beam, and sending them on to the Meson Lab. (Too many particles would over-expose the emulsions and make them useless. Radiation Physics Section and Meson Lab personnel had constructed several monitoring devices to assure that beam could be measured and set for this low intensity.) After a frantic day of last minute preparations, it was decided to go ahead with the initial exposures. The first round of stacks were completed by midnight, and with continued coordination with members of the Acceleration Section, those remaining were exposed by 5:45 a.m. on Wednesday morning, September 20, 1972, just 15 minutes before the end of the available time.

The physicists concerned with the emulsion experiments were: J. Gierula of the Institute of Nuclear Research - Cracow, Poland; David King of the University of Tennessee; P.K. Malhotra of the Tata Institute of Fundamental Research, Bombay, India; G. Thomas of Ball State University, Muncie, Indiana; R. Kaiser and J. Massue of the Center of Nuclear Research -- Strasbourg, France; S. Ozaki and M. Teranaka of Osaka City University, Japan; K. Kui and T. Ogata of Tokyo University, Japan; Jere Lord of the University of Washington; V. Nikitin of Dubna representing M. Tretyakova of the Lebedev Physical Institute, Moscow, U.S.S.R., and Andreas Van Ginneken of NAL.

Following this success, the members of the Meson Laboratory Section continued their preparations for the more complex experiments to come. This included getting ready the 80-ft. long targeting arrangement that allowed six secondary particle beams to share the common target struck by the external proton beam from the accelerator. Preparation was made for operation of the many magnets, collimators, vacuum systems, control systems, etc., of the complex transport systems that carried these particles to experiments placed at various points in the 1,000 ft. long tunnels housing these beam lines. Provisions were made for containment of radiation by a massive overhead covering of soil. Finally, space was provided for the experimenters' equipment in these beam lines, including electrical power systems, water cooling systems, air conditioning systems, and magnets.

The next experiments scheduled for the Meson operations were a quark search and a neutron total cross section measurement. The quark experiment was a hunt for fractionally-charged "quark' particles by physicists from Yale University and Brookhaven National Laboratory, utilizing the normally neutral M4 "KQ" beam as a charged particle path. The neutron total cross section experiment utilized the tunnels of the M3 "neutron" neutral beam and involved physicists from the University of Michigan and Wisconsin.

The nucleus of the Meson Lab group was the old Booster group. Among these were Jim Michelassi, Jan Ryk, Umer Patel, Jim Humbert, Leo Ray, Bud Koecher, Frank Ascolese, Dick Nelson and Joyce Arado. The efforts of Don Richied, Bob Kolar, Bill Lord, Tony Glowacki - among others - contributed to the fine crew of the the Meson Laboratory. Staff physicists of the Meson Laboratory in this effort were Dick Lundy, Klaus Pretzl and Alan Wehman. Valuable contributions in the past toward creation of the Meson Lab were made by a host of others, including Jim Sanford, Lincoln Read, Ed Bleser, Dick Orr, Dick Carrigan, Dave Carey, Dave Eartly, and Roland Juhala - just to single out a heroic few. Groups outside the Section making valuable contributions were the Controls Group under Bob Daniels, the Alignment Group under Bill Testin, and DUSAF represented by Tom Pawlak.

Assisting with the emulsion experiments were Lou Voyvodic (Experiment Coordinator) and Jim Hoover of the Neutrino Lab; Bleser, Gene Fisk, Joe Gomilar, Jack McCarthy, Robert Oberholtzer, Les Oleksiuk, and Claus Rode of the Switchyard Section; Bob Horbis, Leonard Indykiewicz, Randy Ingamells, Kolar, Lundy, Pretzl, Richied, and Dimetrios Zafiropoulos.